In a Ziploc bag, combine zest and juice of 2 limes, mint, brown sugar, garlic, salt and pepper. Add chicken and marinate for 30 minutes. Place chicken, skin-side up on a cookie sheet topped with a baking rack. Bake at 425 for 20-25 minutes or until juices run clear.
Meanwhile, bake sweet potatoes at 350 for 1 hour or until fork tender. Scoop out meats and discard skins. Whip potatoes with lime juice, lime zest, hot sauce, butter and milk until smooth and creamy. Serve chicken on a bed of sweet potatoes topped with reserved, fresh chopped mint.